Does anyone know what the power of the 883 engine in the iron is and how much more could be gained by fitting short shots, filter and fuel pack ?

 

These numbers vary, but stock is right around 45 HP if I remember right. I don't know how much you would gain for certain, but changing exhaust and intake usually nets about 10%.

 

If you change the pipes and air cleaner, with the proper adjustment to the fuel delivery system, you can expect around a 10% increase in horse power, and around 12% increase in torque.

After I did that to my 883 I was putting 53 horse power to the rear wheel.